#pragma once

#include <linux/types.h> /* for size_t */

#ifndef NULL
#define NULL ((void *)0)
#endif

/*
 * This string-include defines all string functions as inline
 * functions. Use gcc. It also assumes ds=es=data space, this should be
 * normal. Most of the string-functions are rather heavily hand-optimized,
 * see especially strtok,strstr,str[c]spn. They should work, but are not
 * very easy to understand. Everything is done entirely within the register
 * set, making the functions fast and clean. String instructions have been
 * used through-out, making for "slightly" unclear code :-)
 *
 *		Copyright (C) 1991, 1992 Linus Torvalds
 */

static inline char *strcpy(char *dest, const char *src) {
    __asm__("cld\n"
            "1:\tlodsb\n\t"
            "stosb\n\t"
            "testb %%al,%%al\n\t"
            "jne 1b"
            : /* no output */
            : "S"(src), "D"(dest));
    return dest;
}

static inline char *strncpy(char *dest, const char *src, size_t count) {
    __asm__("cld\n"
            "1:\tdecl %2\n\t"
            "js 2f\n\t"
            "lodsb\n\t"
            "stosb\n\t"
            "testb %%al,%%al\n\t"
            "jne 1b\n\t"
            "rep\n\t"
            "stosb\n"
            "2:"
            : /* no output */
            : "S"(src), "D"(dest), "c"(count));
    return dest;
}

static inline char *strcat(char *dest, const char *src) {
    __asm__("cld\n\t"
            "repne\n\t"
            "scasb\n\t"
            "decl %1\n"
            "1:\tlodsb\n\t"
            "stosb\n\t"
            "testb %%al,%%al\n\t"
            "jne 1b"
            : /* no output */
            : "S"(src), "D"(dest), "a"(0), "c"(0xffffffff));
    return dest;
}

static inline char *strncat(char *dest, const char *src, size_t count) {
    __asm__("cld\n\t"
            "repne\n\t"
            "scasb\n\t"
            "decl %1\n\t"
            "movl %4,%3\n"
            "1:\tdecl %3\n\t"
            "js 2f\n\t"
            "lodsb\n\t"
            "stosb\n\t"
            "testb %%al,%%al\n\t"
            "jne 1b\n"
            "2:\txorl %2,%2\n\t"
            "stosb"
            : /* no output */
            : "S"(src), "D"(dest), "a"(0), "c"(0xffffffff), "g"(count));
    return dest;
}

static inline int strcmp(const char *cs, const char *ct) {
    register int __res __asm__("ax");
    __asm__("cld\n"
            "1:\tlodsb\n\t"
            "scasb\n\t"
            "jne 2f\n\t"
            "testb %%al,%%al\n\t"
            "jne 1b\n\t"
            "xorl %%eax,%%eax\n\t"
            "jmp 3f\n"
            "2:\tmovl $1,%%eax\n\t"
            "jb 3f\n\t"
            "negl %%eax\n"
            "3:"
            : "=a"(__res)
            : "D"(cs), "S"(ct));
    return __res;
}

static inline int strncmp(const char *cs, const char *ct, size_t count) {
    register int __res __asm__("ax");
    __asm__("cld\n"
            "1:\tdecl %3\n\t"
            "js 2f\n\t"
            "lodsb\n\t"
            "scasb\n\t"
            "jne 3f\n\t"
            "testb %%al,%%al\n\t"
            "jne 1b\n"
            "2:\txorl %%eax,%%eax\n\t"
            "jmp 4f\n"
            "3:\tmovl $1,%%eax\n\t"
            "jb 4f\n\t"
            "negl %%eax\n"
            "4:"
            : "=a"(__res)
            : "D"(cs), "S"(ct), "c"(count));
    return __res;
}

static inline char *strchr(const char *s, char c) {
    register char *__res __asm__("ax");
    __asm__("cld\n\t"
            "movb %%al,%%ah\n"
            "1:\tlodsb\n\t"
            "cmpb %%ah,%%al\n\t"
            "je 2f\n\t"
            "testb %%al,%%al\n\t"
            "jne 1b\n\t"
            "movl $1,%1\n"
            "2:\tmovl %1,%0\n\t"
            "decl %0"
            : "=a"(__res)
            : "S"(s), "0"(c));
    return __res;
}

static inline char *strrchr(const char *s, char c) {
    register char *__res __asm__("dx");
    __asm__("cld\n\t"
            "movb %%al,%%ah\n"
            "1:\tlodsb\n\t"
            "cmpb %%ah,%%al\n\t"
            "jne 2f\n\t"
            "movl %%esi,%0\n\t"
            "decl %0\n"
            "2:\ttestb %%al,%%al\n\t"
            "jne 1b"
            : "=d"(__res)
            : "0"(0), "S"(s), "a"(c));
    return __res;
}

static inline size_t strspn(const char *cs, const char *ct) {
    register char *__res __asm__("si");
    __asm__("cld\n\t"
            "movl %4,%%edi\n\t"
            "repne\n\t"
            "scasb\n\t"
            "notl %%ecx\n\t"
            "decl %%ecx\n\t"
            "movl %%ecx,%%edx\n"
            "1:\tlodsb\n\t"
            "testb %%al,%%al\n\t"
            "je 2f\n\t"
            "movl %4,%%edi\n\t"
            "movl %%edx,%%ecx\n\t"
            "repne\n\t"
            "scasb\n\t"
            "je 1b\n"
            "2:\tdecl %0"
            : "=S"(__res)
            : "a"(0), "c"(0xffffffff), "0"(cs), "g"(ct));
    return __res - cs;
}

static inline size_t strcspn(const char *cs, const char *ct) {
    register char *__res __asm__("si");
    __asm__("cld\n\t"
            "movl %4,%%edi\n\t"
            "repne\n\t"
            "scasb\n\t"
            "notl %%ecx\n\t"
            "decl %%ecx\n\t"
            "movl %%ecx,%%edx\n"
            "1:\tlodsb\n\t"
            "testb %%al,%%al\n\t"
            "je 2f\n\t"
            "movl %4,%%edi\n\t"
            "movl %%edx,%%ecx\n\t"
            "repne\n\t"
            "scasb\n\t"
            "jne 1b\n"
            "2:\tdecl %0"
            : "=S"(__res)
            : "a"(0), "c"(0xffffffff), "0"(cs), "g"(ct));
    return __res - cs;
}

static inline char *strpbrk(const char *cs, const char *ct) {
    register char *__res __asm__("si");
    __asm__("cld\n\t"
            "movl %4,%%edi\n\t"
            "repne\n\t"
            "scasb\n\t"
            "notl %%ecx\n\t"
            "decl %%ecx\n\t"
            "movl %%ecx,%%edx\n"
            "1:\tlodsb\n\t"
            "testb %%al,%%al\n\t"
            "je 2f\n\t"
            "movl %4,%%edi\n\t"
            "movl %%edx,%%ecx\n\t"
            "repne\n\t"
            "scasb\n\t"
            "jne 1b\n\t"
            "decl %0\n\t"
            "jmp 3f\n"
            "2:\txorl %0,%0\n"
            "3:"
            : "=S"(__res)
            : "a"(0), "c"(0xffffffff), "0"(cs), "g"(ct));
    return __res;
}

static inline char *strstr(const char *cs, const char *ct) {
    register char *__res __asm__("ax");
    __asm__("cld\n\t"
            "movl %4,%%edi\n\t"
            "repne\n\t"
            "scasb\n\t"
            "notl %%ecx\n\t"
            "decl %%ecx\n\t" /* NOTE! This also sets Z if searchstring='' */
            "movl %%ecx,%%edx\n"
            "1:\tmovl %4,%%edi\n\t"
            "movl %%esi,%%eax\n\t"
            "movl %%edx,%%ecx\n\t"
            "repe\n\t"
            "cmpsb\n\t"
            "je 2f\n\t" /* also works for empty string, see above */
            "xchgl %%eax,%%esi\n\t"
            "incl %%esi\n\t"
            "cmpb $0,-1(%%eax)\n\t"
            "jne 1b\n\t"
            "xorl %%eax,%%eax\n\t"
            "2:"
            : "=a"(__res)
            : "0"(0), "c"(0xffffffff), "S"(cs), "g"(ct));
    return __res;
}

static inline size_t strlen(const char *s) {
    register int __res __asm__("cx");
    __asm__("cld\n\t"
            "repne\n\t"
            "scasb\n\t"
            "notl %0\n\t"
            "decl %0"
            : "=c"(__res)
            : "D"(s), "a"(0), "0"(0xffffffff));
    return __res;
}

extern char *___strtok;

static inline char *strtok(char *s, const char *ct) {
    register char *__res;
    __asm__("testl %1,%1\n\t"
            "jne 1f\n\t"
            "testl %0,%0\n\t"
            "je 8f\n\t"
            "movl %0,%1\n"
            "1:\txorl %0,%0\n\t"
            "movl $-1,%%ecx\n\t"
            "xorl %%eax,%%eax\n\t"
            "cld\n\t"
            "movl %4,%%edi\n\t"
            "repne\n\t"
            "scasb\n\t"
            "notl %%ecx\n\t"
            "decl %%ecx\n\t"
            "je 7f\n\t" /* empty delimeter-string */
            "movl %%ecx,%%edx\n"
            "2:\tlodsb\n\t"
            "testb %%al,%%al\n\t"
            "je 7f\n\t"
            "movl %4,%%edi\n\t"
            "movl %%edx,%%ecx\n\t"
            "repne\n\t"
            "scasb\n\t"
            "je 2b\n\t"
            "decl %1\n\t"
            "cmpb $0,(%1)\n\t"
            "je 7f\n\t"
            "movl %1,%0\n"
            "3:\tlodsb\n\t"
            "testb %%al,%%al\n\t"
            "je 5f\n\t"
            "movl %4,%%edi\n\t"
            "movl %%edx,%%ecx\n\t"
            "repne\n\t"
            "scasb\n\t"
            "jne 3b\n\t"
            "decl %1\n\t"
            "cmpb $0,(%1)\n\t"
            "je 5f\n\t"
            "movb $0,(%1)\n\t"
            "incl %1\n\t"
            "jmp 6f\n"
            "5:\txorl %1,%1\n"
            "6:\tcmpb $0,(%0)\n\t"
            "jne 7f\n\t"
            "xorl %0,%0\n"
            "7:\ttestl %0,%0\n\t"
            "jne 8f\n\t"
            "movl %0,%1\n"
            "8:"
            : "=b"(__res), "=S"(___strtok)
            : "0"(___strtok), "1"(s), "g"(ct));
    return __res;
}

static inline void *memcpy(void *to, const void *from, size_t n) {
    __asm__("cld\n\t"
            "movl %%edx, %%ecx\n\t"
            "shrl $2,%%ecx\n\t"
            "rep\n\tmovsl\n\t"
            "testb $1,%%dl\n\t"
            "je 1f\n\t"
            "movsb\n"
            "1:\ttestb $2,%%dl\n\t"
            "je 2f\n\t"
            "movsw\n"
            "2:\n"
            : /* no output */
            : "d"(n), "D"((long)to), "S"((long)from));
    return (to);
}

static inline void *memmove(void *dest, const void *src, size_t n) {
    if (dest < src)
        __asm__("cld\n\t"
                "rep\n\t"
                "movsb"
                : /* no output */
                : "c"(n), "S"(src), "D"(dest));
    else
        __asm__("std\n\t"
                "rep\n\t"
                "movsb\n\t"
                "cld"
                : /* no output */
                : "c"(n),
                  "S"(n - 1 + (const char *)src),
                  "D"(n - 1 + (char *)dest));
    return dest;
}

static inline int memcmp(const void *cs, const void *ct, size_t count) {
    register int __res __asm__("ax");
    __asm__("cld\n\t"
            "repe\n\t"
            "cmpsb\n\t"
            "je 1f\n\t"
            "movl $1,%%eax\n\t"
            "jb 1f\n\t"
            "negl %%eax\n"
            "1:"
            : "=a"(__res)
            : "0"(0), "D"(cs), "S"(ct), "c"(count));
    return __res;
}

static inline void *memchr(const void *cs, char c, size_t count) {
    register void *__res __asm__("di");
    if (!count)
        return NULL;
    __asm__("cld\n\t"
            "repne\n\t"
            "scasb\n\t"
            "je 1f\n\t"
            "movl $1,%0\n"
            "1:\tdecl %0"
            : "=D"(__res)
            : "a"(c), "D"(cs), "c"(count));
    return __res;
}

static inline void *memset(void *s, char c, size_t count) {
    __asm__("cld\n\t"
            "rep\n\t"
            "stosb"
            : /* no output */
            : "a"(c), "D"(s), "c"(count));
    return s;
}
